The occupied electronic structure of ultrathin boron doped diamond

At a Glance

Metadata	Details
Publication Date	2020-01-01
Journal	Nanoscale Advances
Authors	A. C. Pakpour-Tabrizi, Alex K. Schenk, Ann Julie Holt, Sanjoy Kr Mahatha, Fabian Arnold
Institutions	Norwegian University of Science and Technology, Russian Academy of Sciences
Citations	10
Analysis	Full AI Review Included

6CCVD Technical Documentation: Boron-Doped Diamond $\delta$-Layers for Nanoscale Electronics

Research Paper Analysis: The occupied electronic structure of ultrathin boron doped diamond (Nanoscale Adv., 2020, 2, 1358-1364)

This document leverages the findings from the cited research to demonstrate 6CCVD’s expertise in providing specialized MPCVD Boron-Doped Diamond (BDD) films necessary for developing next-generation miniaturized electronic components.

Executive Summary

This high-density summary outlines the core findings regarding the electronic properties of nanoscale boron-doped diamond ($\delta$-layers).

Objective: To compare the occupied electronic band structure of ultrathin BDD $\delta$-layers (1.8 nm) against bulk BDD films (3 µm) using Angle-Resolved Photoelectron Spectroscopy (ARPES).
Material Specification: Both samples were heavily boron-doped (~5 x 10²⁰ cm^-3) and grown via Chemical Vapour Deposition (CVD) on (100) HPHT Ib substrates.
Critical Finding: Contrary to theoretical predictions, the occupied electronic structure of the 1.8 nm BDD $\delta$-layer showed no observable quantum confinement effects (i.e., no unique quantum well states).
Observation: The electronic structure of the nanoscale film was almost identical to that of the bulk material, exhibiting only a small, measurable modification in the hole effective mass.
Commercial Implication: The retention of bulk-like electronic properties in BDD down to the nanometer scale (1.8 nm) is highly advantageous for developing stable, miniaturized diamond electrical components, simplifying device design by eliminating quantum confinement concerns.
Methodology: Samples required high-purity CVD growth techniques, an intrinsic diamond buffer layer (0.5 µm), and rigorous UHV thermal preparation (up to 800 °C).

Technical Specifications

The following hard data points were extracted from the research paper, highlighting the precision required for material synthesis and characterization.

Parameter	Value	Unit	Context
Ultrathin BDD Layer Thickness	1.8	nm	Nominal thickness of the $\delta$-layer (approx. 8 atomic layers)
Bulk BDD Film Thickness	3	µm	Comparison sample thickness
Intrinsic Buffer Layer Thickness	0.5	µm	CVD layer grown between $\delta$-layer and substrate
Substrate Orientation	(100)	N/A	High Pressure High Temperature (HPHT) Ib substrate
Sample Lateral Dimension	3.6 x 3.6	mm	Size of substrates used for film growth
Boron Doping Concentration	~5 x 10²⁰	cm^-3	Doping density determined by SIMS in both thin and bulk films
Sample Cleaning Anneal	350	°C	Held for 8 hours in situ
Sample Cleaning Flash Temp	800	°C	Multiple 5 second flashes in UHV
Estimated Hole Effective Mass (m_lh)	0.263 to 0.309	m_o	Literature values for light hole mass (m_o = free electron mass)
Inner Potential (ARPES)	22	eV	Value used for free-electron final state model conversion

Key Methodologies

The experiment relied on highly controlled Chemical Vapour Deposition (CVD) to achieve precise doping profiles and thicknesses, followed by specialized vacuum preparation.

Substrate Selection: Use of (100) oriented HPHT Ib diamond substrates (3.6 mm x 3.6 mm) to ensure high crystallinity for epitaxial growth.
Intrinsic Buffer Layer: Growth of a 0.5 µm intrinsic diamond layer via CVD to buffer the doped layer from the substrate.
Boron Doping via CVD: Boron precursor introduced during CVD growth to achieve extremely sharp, heavily doped $\delta$-layers (1.8 nm) and bulk films (3 µm).
Dopant Concentration Control: Precise control of CVD parameters resulting in a boron doping density near 5 x 10²⁰ cm^-3, verified post-growth by Secondary-Ion Mass Spectrometry (SIMS).
UHV Thermal Cleaning: Samples were annealed in ultra-high vacuum (UHV) for eight hours at 350 °C, followed by high-temperature flashing up to 800 °C to remove atmospheric contaminants prior to ARPES.
Band Structure Analysis: Angle-Resolved Photoelectron Spectroscopy (ARPES) was utilized across high photon energy ranges (380-460 eV) to probe the occupied electronic structure and compare band dispersions (E(k)) between the thin and bulk films.
Effective Mass Determination: Comparison of parabolic band maxima dispersion near the Fermi level (E_F) to determine effective hole mass modification in the ultrathin layer.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to support and extend this research on Boron-Doped Diamond $\delta$-layers, providing custom materials that meet the stringent requirements of advanced surface physics and nanoscale device fabrication.

Applicable Materials

To replicate or advance this study, researchers require tightly controlled, high-quality diamond films. 6CCVD offers the necessary materials via our proprietary MPCVD process:

Boron-Doped Diamond (BDD): We supply heavily doped BDD films, ideal for metallic conductivity and superconductivity studies, capable of achieving the high concentrations (up to 5 x 10²⁰ cm^-3) utilized in this paper.
Single Crystal Diamond (SCD) Plates: High-purity, intrinsic SCD is essential for the buffer layer and host material, ensuring minimum defects and maximum crystalline quality. We offer SCD in thicknesses from 0.1 µm to 500 µm.
Custom Substrates: We provide thick SCD substrates up to 10 mm, suitable for fundamental research or specialized device architectures, acting as a superior alternative or complement to HPHT Ib substrates.

Customization Potential

The success of nanoscale BDD research hinges on dimensional precision and material integration. 6CCVD’s comprehensive capabilities minimize variability and accelerate experimental throughput.

Requirement Addressed	6CCVD Capability	Research Benefit
Nanoscale Thickness Control	SCD and BDD layer growth from 0.1 µm to 500 µm, allowing atomic-layer precision necessary for exploring quantum confinement effects.	Enables systematic exploration of thickness dependence (e.g., 8-layer vs. 4-layer films) to fully map the quantum-to-bulk transition.
Large Area Scalability	Custom plates/wafers available up to 125 mm (PCD) and large-area SCD, far exceeding the 3.6 mm samples used in the paper.	Crucial for scaling up successful lab-scale designs into manufacturable piezoresistive sensors or large-array quantum platforms.
Surface Quality for ARPES	Ultra-smooth polishing services: Ra < 1 nm (SCD) and Ra < 5 nm (PCD).	Guarantees atomically flat surfaces required for reliable UHV/ARPES measurements sensitive to surface reconstruction and band mapping.
Electrical Integration	Internal Metalization Services: Capabilities include sputtering or evaporation of Au, Pt, Pd, Ti, W, and Cu contacts.	Allows for immediate integration of contacts or gate structures (Schottky contacts) discussed in the paper’s theoretical models, streamlining device prototyping.

Engineering Support

The paper noted significant discrepancies between theoretical predictions and experimental observations regarding quantum confinement in BDD.

6CCVD’s in-house PhD material science team specializes in resolving these complex material-property correlations. We offer dedicated support for projects related to nanoscale electronic structure, high-frequency transport, and superconducting diamond applications. Our expertise ensures that material parameters like doping profile sharpness, defect density, and layer stacking are optimized to achieve specific electronic outcomes, whether pursuing bulk-like properties or confirmed quantum confined states.

Call to Action: For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. We ship globally (DDU default, DDP available) to support your cutting-edge diamond research.

View Original Abstract

Using angle-resolved photoelectron spectroscopy, we compare the electronic band structure of an ultrathin (1.8 nm) δ-layer of boron-doped diamond with a bulk-like boron doped diamond film (3 μm).

Tech Support

Original Source

DOI: https://doi.org/10.1039/c9na00593e